First off, we are not going to be discussing the biology of xenomorphs because, without a doubt, attempting to study a xenomorph would be a major health hazard leading to probable death…and they are also not real, which certainly helps to ease our fears going into this.
To sum, xenobiology is the creation and manipulation of novel biological systems such as using nucleic acids that are not DNA or RNA, but rather Xeno (strange) nucleic acid (XNA) . In normal biological systems, like you or I, our genome is made up of DNA, which produces RNA and, subsequently, amino acids. This, in turn, results in the formation of who we are physically (and probably mentally) with some exceptions. The goal of a xenobiologist would be to create an organism that is able to live in our world, but its genetics is made up of XNA, forming the synthetic or artificial genome. It is, in a way, like a robot that is made to look exactly like a human or another animal. On the surface, everything might look the same as a human, but if you examine closer it is made of something else (in this case a synthetic biological system and in the case of the robot, metal and stuff).
To make a xenobiological organism, there are a few steps that we need to complete. First, we need to create a stable XNA genome . Like your DNA-based genome, it should encode for all of the functions of your body and also be malleable. Starting out, however, the organism created from this would be very simple like a single-celled organism without many complex features because this is a very difficult process. The next step would be for the XNA to be able to creature secondary structures using only a single strand of XNA (versus two strands for the genome part) because that would play the role of RNA in the system. The third step would be to create XNA-based proteins that are able to function the same as DNA-based proteins to replicate the genome, turn it into X-RNA (the single-stranded secondary structures), and make more XNA proteins .
If these steps are successful then you have an organism that is capable of performing any task that its DNA counterparts can do and can undergo extensive changes with little or no effect on naturally existing organisms. This is because these XNA organisms would be completely incompatible with naturally occurring genomes. Their artificial nature makes them a sort of firewall that stops interactions with the natural world on an individual basis, but would not be entirely problem free.
So, the big question is why would scientists do this? One of the greatest potentials about xenobiology is that there is no need to perform genetic tests on naturally existing species because xeno-organisms could potentially become a surrogate for them if they can replicate natural behaviours . This would be perfect in drug trials, testing vaccine safety, food safety, and many other tests for things that may affect humans or any natural systems. One example of its potential would be to modify it and test its ability to survive in a variety of environments. This is especially important in today’s world with the growing interest in the potential of life on Mars. We would be able to manipulate a xenobiological organism to act like extremophiles that are capable of surviving on Mars or other extreme environments.
Xenobiology is not without its share of pitfalls. The biggest pitfall is that it is difficult to create the XNAs, and in the short term, it would offer no help to science because there is currently no xeno-organism to study. I mentioned that it was a firewall that protected the natural world on an individual level, but it poses a great risk on an ecological level when looking at groups and large habitats . If released into the environment, by accident hopefully, xeno-organisms could become invasive and threaten the existence of organisms in whatever ecosystem it invades. A perfect example would be if we created a xeno-organism to convert our garbage into fuel but it goes awry and it ends up consuming us instead. Or, if we create a xeno-organism to contain greenhouse gases, but they evolve beyond that and suffocate us. These are obviously an exaggeration but something along those lines, though less dramatic, is possible. If they are capable of evolving, they might even break through that genetic firewall and begin interacting with natural species. Then, it could end up like a xenomorph situation, which did not end well in that fictional world.
Adding xeno-organisms into the environment would also challenge many ideas of conservation because questions will arise as to how much they add to biodiversity in the environment if they add anything at all . As with naturally existing life, these synthetic life forms could potentially evolve and understanding what effects that evolution would have on natural systems would be difficult to predict, especially in the early stages of their development . If or when these xeno-organisms become a part of the natural environment, then conservationists and the world, alike, will be faced with the dilemma of defining what it means to be “natural” because these synthetic organisms may integrate into the ecosystem into which they are introduced and form relationships with the organisms around it .
Image of Xenomorph: Courtesy 20th Century Fox and from the film Alien vs Predator. Acquired from Wikipedia Commons